Abstract. The present paper aims to provide first information about invertebrates (bryozoans, serpulids, spirorbids, ostracods and foraminifers) associated to selected Cystoseira communities, from the Ciclopi Islands Marine Protected Area, also contributing knowledge on distribution patterns.
Keywords: bryozoans, serpulids, spirorbids, ostracods, foraminifers, algae, Ionian Sea
First information on bryozoans, serpuloideans, ostracods and foraminifers from shallow-water communities sampled in the frame of the CIMPA-BioChange Project (Biodiversity and spatio-temporal variations of Cystoseira communities of the Biocoenosis of the Infralittoral Algae from the Ciclopi Islands Marine Protected Area, Ionian Sea) is presented.
Samples were collected in June 2015, in two sites with three stations each, few km north of Catania: Punta Aguzza (Acicastello), within the Ciclopi Islands MPA, Santa Maria La Scala and Santa Tecla (Acireale), outside the CIMPA. Communities in the Cystoseira brachycarpa, C. sauvageauana and C. spinosa, were sampled at 5, 9, and 25 m depth, respectively.
Bryozoans are present with more than 50 species, consisting mostly of cheilostomes (41 species) and subordinate cyclostomes and ctenostomes. However, several cyclostome species (particularly Crisia spp. and Patinella radiata) are dominant, with a high number of colonies. Cheilostomes, instead, are represented by single or few colonies, except for Aetea spp., Copidozoum tenuirostre and some celleporiids.
Among serpuloideans, 20 species (14 serpulids and 6 spirorbids) have been detected. Spirorbids are greatly dominant in terms of specimens, mainly belonging to Pileolaria spp., Janua spp. and Spirorbis cuneatus. Serpulids are mostly represented by Josephella marenzelleri and Pomatoceros triqueter, followed by Vermiliopsis straticeps and Serpula vermicularis.
Ostracods include some 25 species, that are all known from shallow-water vegetate bottoms. Species belonging to the genera Xestoleberis (especially X. dispar) and Paradoxostoma largely prevail.
Foraminifers are represented by more than 30 species. Miliolids dominate (mostly with some Quinqueloculina species) followed by Elphidium representatives. Nearly all species were found on the algal thalli.
Overall, invertebrate communities show low cover values. A general trend of increasing species diversity can be traced from the shallowest to the deepest communities. The number of specimens/colonies for each of the taxonomic group analysed appears to be related to the availability of suitable microhabitats and substrata created by the hosting algal species. Differences are also evident between the two sites, with samples collected within the CIMPA, characterised by a lower species diversity and specimen/colony abundance, in relation to those collected outside the MPA.
Patterns of distribution were also evident for encrusting bryozoans, with some species restricted to, or preferentially colonising the basal or the top parts of the algal thalli. Adult serpuloidean specimens were mostly localised on the axial thicker algal portions that provide a relatively firm substratum. Bryozoan colonies are invariably small but fertile, thus pointing to dominant r-strategy, as a special adaptation to the ephemeral substratum offered by the algae.
Fig. 1. A. The ostracod Bairdia longevaginata. Scale bar: 200 m. Sample SM.1.S9. B. The foraminifer Cibicides advenum. Scale bar: 200 m. Sample CPA.1.Z26. C. The bryozoan Aetea anguina on Halopteris scoparia. Scale bar: 1 mm. Sample ST.1.Z9. D. The bryozoan Patinella radiata on Halopteris scoparia. Scale bar: 2 mm. Sample ST.1.Z9. E. The spirorbid Pileolaria pseudomilitaris on Halopteris scoparia. Scale bar: 1mm. Sample CPA.1.Z26. F. The serpulids Josephella marenzelleri (left) and Serpula concharum (right). Scale bar: 5 mm. Sample SM.1.Z25.